Looking to the LTx gurus here for this one. I just finished putting my LT1 back together. The combo is internally the same, only major difference is an MSD Opti and EWP (Got the opti when they first came out and it's still new never used.)

There is no exhaust on the car, just open headers with brand new o2 sensors plugged in and hanging in the air.

When I crank the car over, it will pop and shoot brief flames out the headers, but does not start. I see oil pressure building at the gauge as it cranks.

I started to verify plug wire order, but stopped because I needed a 2nd person to look from the top. I', not even sure I'll be able to look at the numbers on the front of the opti without pulling half the car apart.

Any ideas other than plug wire order?

 

http://shbox.com/1/opti.jpg

Have you checked the fuel pressure?

 

Some opti's can be installed wrong and if you had to force it a little it might be install incorrectly. Not sure what years but it happens alot.

 

I have not checked fuel pressure. What should it be at startup? I know that my FMU varies it with RPM but what should it be with just the key turned to "on." BTW, Do you know if it is ok to disconnect the FMU so that I can tap into the fuel rail with a fuel pressure gauge?

 

The opti went on like butter. It originally came with the wrong round style O-ring as did all the first MSD optis, but before I installed it I got the correct square style o-ring. Nontheless, the opti went on smooth and seated well.

 

Turn the key and the fuel system should prime to ~42psi. Your FMU should increase the pressure proportional to boost, not RPM. Unless you have removed the stock fuel supply piping, you already have a tap for a fuel pressure gauge - the Schrader valve, behind the manifold, on the fuel supply hardline.

It is possible to get the Opti dowel pin in the wrong hole, in which cast the timing will be 120 cam degrees off.

Leaving the O2 sensors hanging in free air will be a problem if it does start up. The PCM will not go into closed loop, because the O2 sensors will not heat up. If it did go into closed loop, it would run rich because the O2 sensors are exposed to air, not exhaust. But on a cold start, they aren't going to be a problem, since the PCM should have 0% long term fuel trims (128 BLM's).

The MSD Opti's, particularly the "original" ones are know for having the rotor fall off. Did you lok-tite the screws before you installed it? The early ones also had problems with warped optical discs.

Have you scanned it for codes?

Just curious, from a Moderator point of view - why did you post this in "General...." rather than in "LT1 Based Engine Tech"?

 

Oops wrong forum....feel free to move it...sorry bout that

I just spent a bunch of time on shoebox's site, looking at all the connections, etc. This weekend I'll take the laptop to the car and verify as many connections as possible.

The FMU is connected to the schrader valve on the fuel rail. Would it be okay to disconnect the FMU in order to test fuel pressure? I don't see why not as long as I don't start the car.

About the opti...If after verifying as many vacuum connections, etc, as well as plug wire order it still acts the same, I'll pull opti and verify the dowel pin location.

Thanks for the help....I've got a busy/messy Sunday coming up

 

Just realized I never updated this thread. The problem ended up being the valves were way out of adjustment and 2 plug wires were crossed. Doh!